Poly(2,5-benzimidazole)/trisilanolphenyl POSS composite membranes for intermediate temperature PEM fuel cells

Novel organic-inorganic composites were in-situ synthesized by using TriSilanolPhenyl polyhedral oligomeric silsesquioxane (SO-POSS) as fillers and poly(2,5-benzimidazole) (ABPBI) as polymer matrix. The uniformly dispersed 3% SO-POSS particles in ABPBI matrix increased the thermal stability of the composite membranes. It was found that both the water and H 3 PO 4 uptakes were increased significantly with the addition of SO-POSS due to the formation of hydrogen bonds between the POSS and H 2 O/H 3 PO 4 , which played a critical role in the improvement of the conductivity of the composite membranes at temperature over 100 °C. Proton conductivities of H 3 PO 4 doped with 3wt% SO-POSS contained ABPBI membranes increased with the increase of H 3 PO 4 absorbance, reaching the maximum proton conductivity of 2.55 × 10 -3 S·cm -1 at 160 °C, indicating that the ABPBI/SO-POSS composite membrane could be a promising candidate for mid-temperature PEMFCs.